GGT1 and colorectal cancer: GGT V is found mainly in colorectal cancer tissues (91.7%) and paracancerous tissues (72.7%), and the GGT V positivity rate is not correlated with Dukes' stage of colorectal cancer or with the degree of differentiation; moreover, its isoelectric point is consistent with the isoelectric point of placental type GGT (PGGT V).